1. Field
The present disclosure relates to a cooling structure of an internal combustion engine.
2. Description of the Related Art
Development of technology has been pursued to increase the efficiency in cooling an inter-bore region (also referred to as an inter-axis region) that is located between adjacent cylinder bores and extends in the width direction of a cylinder block in a cooling structure of an internal combustion engine. For example, Japanese Unexamined Patent Application Publication No. 2012-225246 (claim 1, FIG. 2) discloses a structure in which an inter-bore region is provided with an inter-bore cooling passage, a gasket hole is provided outwardly of an opening of the inter-bore cooling passage in the direction of the width of a cylinder block, the opening facing the cylinder head, and a head hole is further provided outwardly of the gasket hole in the width direction for the purpose of increasing the amount of coolant by reducing a pressure loss. Japanese Patent No. 4770828 (claim 1, FIG. 3) discloses a gasket, in which a coolant hole, which communicates with coolant passages formed in a cylinder head and a cylinder block, is extended for an opening of a coolant passage only in the direction away from the center line of arranged bore holes (also referred to as the cylinder bank center line) in a gasket which is formed in an region between adjacent bore holes, the opening through the top surface of the cylinder block.